1-3
This is the easiest level in world 1. The two tiers are separated by doing either a single jump or a triple jump for 1-3 skip. Triple jumps give 1 extra block of height which makes the skip more lenient, but loses anywhere from a little to about an igt.
The Triple jump at the start of 1-3 ensures that we can avoid the hammer bros RNG 100% of the time.